1. Field of the Invention
The present invention relates to ratchet mechanisms and, in particular, to ratchet wrenches of the reversible type having a manually-operated reversing member. The invention relates in particular to seals for the ratchet mechanism.
2. Description of the Prior Art
The present invention is an improvement of the reversible ratchet wrench disclosed in U.S. Pat. No. 5,495,783, the disclosure of which is incorporated herein by reference. Accordingly, only so much of the construction of the ratchet wrench will be described in detail herein as is necessary for an understanding of the present invention.
In the wrench of U.S. Pat. No. 5,495,783, a handle with a circular ratchet head has a cylindrical array of internal ratchet teeth defining a cavity, which receives coaxially rotatably therein a drive body. A pawl is carried by the drive body for movement between forward and reverse conditions of engagement with the ratchet teeth, being retained in each of these positions by an over-center spring engageable with a pin on a reversing lever. The reversing lever is disposed coaxially with the drive body and retained thereon by a bushing and a screw for rotation relative to the drive body and the ratchet head to shift the pawl between its forward and reverse conditions. Annular recesses are formed at each end of the head coaxial with the cavity, and respectively face corresponding annular recesses on the drive body and reversing lever, for cooperation therewith to define annular spaces in which are respectively received annular seal members to retain lubricant in the cavity and prevent the entry of dust and dirt therein. The seals are radial seals, with each seal being disposed between and resiliently engaging opposed cylindrical surfaces of the corresponding recesses. It has been found that the radial compressive force on the radial seals necessary to maintain an effective seal creates a significant frictional drag on the rotating parts, necessitating a significant torque to effect both the ratcheting operation and manual operation of the reversing member.